Display technologies based on encapsulation of electrophoretic particles, multichromal beads and liquid crystals are known in fields such as electronic paper and other digital document media. Examples of electronic display devices using such materials include those available from Gyricon LLC of Ann Arbor, Mich. For example, as shown in FIG. 1, a group of encapsulated bichromal beads, cylinders, crystals or other bichromal or multichromal particles 10 are dispersed in an elastomeric sheet swollen by a fluid 12 and positioned atop a conductive substrate 14, which is typically a printed circuit board or other conductive material. The particles, fluid and substrate are covered with a transparent layer 16 such as glass or plastic and a transparent conductive material such as indium tin oxide (ITO) 18, and they are sealed to form a re-addressable display material in which the particles rotate in response to an electric or magnetic field that is applied to the conductive substrate. Such materials have been described in, for example, U.S. Pat. No. 4,126,854 to Sheridon and U.S. Pat. No. 4,143,103 to Sheridon, the disclosures of each of which are incorporated herein by reference in their entirety.
Bichromal displays have numerous advantages over conventional electrically addressable visual displays, such as LCD and CRT displays. In particular, they are suitable for viewing in ambient light, they retain an image indefinitely in the absence of an applied electric field, and they can be made lightweight, flexible, foldable, and with many other familiar and useful characteristics of ordinary writing paper. Thus, at least in principle, they are suitable both for display applications and for so-called electric paper or interactive paper applications, in which they serve as an electrically addressable, reusable substitute for ordinary paper. Bichromal displays have been used in several applications, such as in displays on compact disks and floppy disks as described in U.S. Pat. Nos. 6,611,271 and 6,476,817, respectively, each of which is incorporated herein by referenced in its entirety.
Transaction cards are common. Transaction cards are typically thin plastic or paper cards in a rectangular shape that have one or more magnetic strips. The cards are typically used for identification, access or for financial transactions. While display areas have been placed on transaction cards previously, prior transaction cards have been unable to achieve a lasting, changeable display that does not need a power source. In U.S. Pat. No. 6,019,284, the transaction card contains a display area that is powered by a power source. In U.S. Pat. No. 5,359,183, the use of the display on the card is electromagnetic and displays a value. However, it will only remain on the card for a limited period of time as the display may change as the card is moved or exposed to even a minor magnetic force.
Accordingly, a need exists for an improved transaction card with a rewriteable display area.